FDC37C669 datasheet(11/164 Pages) SMSC

11 / 164 page

DESCRIPTION OF PIN FUNCTIONS

QFP/

TQFP

PIN NO.

NAME

SYMBOL

BUFFER

TYPE

DESCRIPTION

84,86

nRing Indicator

nRI1

nRI2

Active low Ring Indicator inputs for the

serial port. Handshake signal which notifies

the UART that the telephone ring signal is

detected by the modem.

The CPU can

monitor the status of nRI signal by reading

bit 6 of Modem Status Register (MSR). A

nRI signal state change from low to high

after the last MSR read will set MSR bit 2 to

a 1. If bit 3 of Interrupt Enable Register is

set, the interrupt is generated when nRI

changes state. Note: Bit 6 of MSR is the

complement of nRI.

PARALLEL PORT INTERFACE

nPrinter Select

Input

nSLCTIN

OD24

0P24

This active low output selects the printer.

This is the complement of bit 3 of the Printer

Control Register.

Refer to Parallel Port description for use of

this pin in ECP and EPP mode.

nInitiate Output

nINIT

OD24

0P24

This output is bit 2 of the printer control

when low.

Refer to Parallel Port description for use of

this pin in ECP and EPP mode.

nAutofeed

Output

nAUTOFD

OD24

0P24

This output goes low to cause the printer to

automatically feed one line after each line is

printed.

The nAUTOFD output is the

complement of bit 1 of the Printer Control

Refer to Parallel Port description for use of

this pin in ECP and EPP mode.

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